Back for a chair



FIG. 1 is a side perspective of a back for a chair showing my new design.

FIG. 2 is a rear elevational view of FIG. 1.

FIG. 3 is a side elevational view of FIG. 1; and,

FIG. 4 is a side elevational view of the other side to that shown in FIG. 3.

The portion of the chair shown in dotted outline in the drawings does not form part of the claimed design. 

The ornamental design for a back for a chair, as shown and described. 